In MRI (Magnetic Resonance Imaging), an intravascular contrast agent is used to ensure high-contrast images. Conventional intravascular MRI contrast agents are dedicated to observation of an overall vascular silhouette, i.e., the degree of stricture in the vascular lumen to provide information for the diagnosis and treatment of vascular diseases, and they cannot be applied for directly detecting lesion sites where the vascular endothelia have exfoliated.
The ability to image the exfoliated vascular endothelia directly as they are would greatly contribute to early disease detection and treatment. However, there are found almost no MRI contrast agents developed for such purpose. A method has been proposed for detecting injured or inflamed vascular sites, in which there are used antibodies against integrin or fibrin as targeting moiety in the MRI contrast agents (D. A. Sipkins et al., Nature Medicine, 4, 623-626 (1998); S. Flacke et al., Circulation, 104, 1280-1285 (2001)). However, such antibody-based contrast agents are not practical as they are costly because they require complicated steps to prepare and have to be used in a large amount.
The object of the invention is to provide a novel MRI contrast agent which enables direct detection and imaging of exfoliated vascular endothelial sites and which is easy to prepare and inexpensive to use.